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Add Source Generator which adds virtual interface methods to C#
sorta like C# 8 default interface methods, but the base implementations are filled in at compile-time
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| namespace BizHawk.Analyzers; | ||
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| public static class Extensions | ||
| { | ||
| public static string RemovePrefix(this string str, string prefix) | ||
| => str.StartsWith(prefix) ? str.Substring(prefix.Length, str.Length - prefix.Length) : str; | ||
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| public static void SwapReferences<T>(ref T a, ref T b) | ||
| { | ||
| ref T c = ref a; // using var results in CS8619 warning? | ||
| a = ref b; | ||
| b = ref c; | ||
| } | ||
| } |
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9 changes: 9 additions & 0 deletions
9
ExternalProjects/BizHawk.SrcGen.VIM/BizHawk.SrcGen.VIM.csproj
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| <Project Sdk="Microsoft.NET.Sdk"> | ||
| <PropertyGroup> | ||
| <TargetFramework>netstandard2.0</TargetFramework> | ||
| </PropertyGroup> | ||
| <Import Project="../AnalyzersCommon.props" /> | ||
| <ItemGroup> | ||
| <EmbeddedResource Include="VirtualMethodAttribute.cs" /> | ||
| </ItemGroup> | ||
| </Project> |
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| namespace BizHawk.SrcGen.VIM; | ||
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| using System; | ||
| using System.Collections.Generic; | ||
| using System.Linq; | ||
| using System.Text; | ||
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| using BizHawk.Analyzers; | ||
| using BizHawk.Common; | ||
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| using Microsoft.CodeAnalysis; | ||
| using Microsoft.CodeAnalysis.CSharp; | ||
| using Microsoft.CodeAnalysis.CSharp.Syntax; | ||
| using Microsoft.CodeAnalysis.Text; | ||
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| using ImplNotesList = System.Collections.Generic.Dictionary<string, System.Collections.Generic.List<BizHawk.SrcGen.VIM.VIMGenerator.ImplNotes>>; | ||
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| [Generator] | ||
| public sealed class VIMGenerator : ISourceGenerator | ||
| { | ||
| internal readonly struct ImplNotes | ||
| { | ||
| public readonly string AccessorKeyword; | ||
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| public readonly string BaseImplNamePrefix; | ||
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| public readonly string InvokeCall; | ||
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| public readonly bool IsSetOrRemove | ||
| => MethodSym.MethodKind is MethodKind.PropertySet or MethodKind.EventRemove; | ||
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| public readonly string MemberFullNameArgs; | ||
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| public readonly IMethodSymbol MethodSym; | ||
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| public readonly string ReturnType; | ||
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| public ImplNotes(IMethodSymbol methodSym, string memberFullNameArgs, string baseImplNamePrefix) | ||
| { | ||
| BaseImplNamePrefix = baseImplNamePrefix; | ||
| MemberFullNameArgs = memberFullNameArgs; | ||
| MethodSym = methodSym; | ||
| switch (methodSym.MethodKind) | ||
| { | ||
| case MethodKind.Ordinary: | ||
| AccessorKeyword = string.Empty; | ||
| InvokeCall = $"(this{string.Concat(methodSym.Parameters.Select(static pSym => $", {pSym.Name}"))})"; | ||
| MemberFullNameArgs += $"({string.Join(", ", methodSym.Parameters.Select(static pSym => $"{pSym.Type.ToDisplayString()} {pSym.Name}"))})"; | ||
| ReturnType = methodSym.ReturnType.ToDisplayString(); | ||
| break; | ||
| case MethodKind.PropertyGet: | ||
| AccessorKeyword = "get"; | ||
| InvokeCall = "(this)"; | ||
| ReturnType = methodSym.ReturnType.ToDisplayString(); | ||
| break; | ||
| case MethodKind.PropertySet: | ||
| AccessorKeyword = "set"; | ||
| InvokeCall = "(this, value)"; | ||
| ReturnType = ((IPropertySymbol) methodSym.AssociatedSymbol!).Type.ToDisplayString(); // only used for set-only props | ||
| break; | ||
| case MethodKind.EventAdd: | ||
| AccessorKeyword = "add"; | ||
| InvokeCall = "(this, value)"; | ||
| ReturnType = $"event {((IEventSymbol) methodSym.AssociatedSymbol!).Type.ToDisplayString()}"; | ||
| break; | ||
| case MethodKind.EventRemove: | ||
| AccessorKeyword = "remove"; | ||
| InvokeCall = "(this, value)"; | ||
| ReturnType = string.Empty; // unused | ||
| break; | ||
| default: | ||
| throw new InvalidOperationException(); | ||
| } | ||
| if (!string.IsNullOrEmpty(AccessorKeyword)) BaseImplNamePrefix += $"_{AccessorKeyword}"; | ||
| } | ||
| } | ||
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| private sealed class VIMGenSyntaxReceiver : ISyntaxReceiver | ||
| { | ||
| public readonly List<TypeDeclarationSyntax> Candidates = new(); | ||
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| public void OnVisitSyntaxNode(SyntaxNode syntaxNode) | ||
| { | ||
| if (syntaxNode is TypeDeclarationSyntax syn) Candidates.Add(syn); | ||
| } | ||
| } | ||
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| private static readonly DiagnosticDescriptor DiagCantMakeVirtual = new( | ||
| id: "BHI2000", | ||
| title: "Only apply [VirtualMethod] to (abstract) methods and property/event accessors", | ||
| messageFormat: "Can't apply [VirtualMethod] to this kind of member, only methods and property/event accessors", | ||
| category: "Usage", | ||
| defaultSeverity: DiagnosticSeverity.Warning, | ||
| isEnabledByDefault: true); | ||
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| #if false | ||
| private static readonly DiagnosticDescriptor DiagDebug = new( | ||
| id: "BHI2099", | ||
| title: "debug", | ||
| messageFormat: "{0}", | ||
| category: "Usage", | ||
| defaultSeverity: DiagnosticSeverity.Warning, | ||
| isEnabledByDefault: true); | ||
| #endif | ||
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| //TODO warning for attr used on member of class/struct/record? | ||
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| //TODO warning for only one of get/set/add/remove pair has attr? | ||
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| //TODO warning for unused base implementation (i.e. impl/override exists in every direct implementor)? ofc the attribute can be pointing to any static method, so the base implementation itself shouldn't be marked unused | ||
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| public void Initialize(GeneratorInitializationContext context) | ||
| => context.RegisterForSyntaxNotifications(static () => new VIMGenSyntaxReceiver()); | ||
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| public void Execute(GeneratorExecutionContext context) | ||
| { | ||
| if (context.SyntaxReceiver is not VIMGenSyntaxReceiver receiver) return; | ||
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| // boilerplate to get attr working | ||
| var compilation = context.Compilation; | ||
| var vimAttrSymbol = compilation.GetTypeByMetadataName("BizHawk.Common." + nameof(VirtualMethodAttribute)); | ||
| if (vimAttrSymbol is null) | ||
| { | ||
| var attributesSource = SourceText.From(typeof(VIMGenerator).Assembly.GetManifestResourceStream("BizHawk.SrcGen.VIM.VirtualMethodAttribute.cs")!, Encoding.UTF8, canBeEmbedded: true); | ||
| context.AddSource("VirtualMethodAttribute.cs", attributesSource); | ||
| compilation = context.Compilation.AddSyntaxTrees(CSharpSyntaxTree.ParseText(attributesSource, (CSharpParseOptions) ((CSharpCompilation) context.Compilation).SyntaxTrees[0].Options)); | ||
| vimAttrSymbol = compilation.GetTypeByMetadataName("BizHawk.Common." + nameof(VirtualMethodAttribute))!; | ||
| } | ||
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| Dictionary<string, ImplNotesList> vimDict = new(); | ||
| ImplNotesList Lookup(INamedTypeSymbol intfSym) | ||
| { | ||
| var fqn = intfSym.FullNamespace(); | ||
| if (vimDict.TryGetValue(fqn, out var implNotes)) return implNotes; | ||
| // else cache miss | ||
| ImplNotesList implNotes1 = new(); | ||
| static (string? ImplsClassFullName, string? BaseImplMethodName) ParseVIMAttr(AttributeData vimAttr) | ||
| { | ||
| string? baseImplMethodName = null; | ||
| string? implsClassFullName = null; | ||
| foreach (var kvp in vimAttr.NamedArguments) switch (kvp.Key) | ||
| { | ||
| case nameof(VirtualMethodAttribute.BaseImplMethodName): | ||
| baseImplMethodName = kvp.Value.Value?.ToString(); | ||
| break; | ||
| case nameof(VirtualMethodAttribute.ImplsClassFullName): | ||
| implsClassFullName = kvp.Value.Value?.ToString(); | ||
| break; | ||
| } | ||
| return (implsClassFullName, baseImplMethodName); | ||
| } | ||
| void AddMethodNotes(IMethodSymbol methodSym, (string? ImplsClassFullName, string? BaseImplMethodName) attrProps) | ||
| { | ||
| var memberName = methodSym.MethodKind is MethodKind.Ordinary ? methodSym.Name : methodSym.AssociatedSymbol!.Name; | ||
| var memberFullNameArgs = $"{intfSym.FullNamespace()}.{memberName}"; | ||
| var baseImplNamePrefix = $"{(attrProps.ImplsClassFullName ?? $"{intfSym.FullNamespace()}.MethodDefaultImpls")}.{attrProps.BaseImplMethodName ?? memberName}"; | ||
| if (!implNotes1.TryGetValue(memberFullNameArgs, out var parts)) parts = implNotes1[memberFullNameArgs] = new(); | ||
| parts.Add(new(methodSym, memberFullNameArgs: memberFullNameArgs, baseImplNamePrefix: baseImplNamePrefix)); | ||
| } | ||
| foreach (var memberSym in intfSym.GetMembers()) | ||
| { | ||
| var vimAttr = memberSym.GetAttributes().FirstOrDefault(ad => vimAttrSymbol.Matches(ad.AttributeClass)); | ||
| switch (memberSym) | ||
| { | ||
| case IMethodSymbol methodSym: // methods and prop accessors (accessors in interface events are an error without DIM) | ||
| if (vimAttr is null) continue; | ||
| if (methodSym.MethodKind is not (MethodKind.Ordinary or MethodKind.PropertyGet or MethodKind.PropertySet)) | ||
| { | ||
| // no idea what would actually trigger this | ||
| context.ReportDiagnostic(Diagnostic.Create(DiagCantMakeVirtual, vimAttr.ApplicationSyntaxReference!.GetSyntax().GetLocation())); | ||
| continue; | ||
| } | ||
| AddMethodNotes(methodSym, ParseVIMAttr(vimAttr)); | ||
| continue; | ||
| case IPropertySymbol propSym: // props | ||
| if (vimAttr is null) continue; | ||
| var parsed = ParseVIMAttr(vimAttr); | ||
| if (propSym.GetMethod is {} getter) AddMethodNotes(getter, parsed); | ||
| if (propSym.SetMethod is {} setter) AddMethodNotes(setter, parsed); | ||
| continue; | ||
| case IEventSymbol eventSym: // events | ||
| if (vimAttr is null) continue; | ||
| var parsed1 = ParseVIMAttr(vimAttr); | ||
| AddMethodNotes(eventSym.AddMethod!, parsed1); | ||
| AddMethodNotes(eventSym.RemoveMethod!, parsed1); | ||
| continue; | ||
| } | ||
| } | ||
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| return vimDict[fqn] = implNotes1; | ||
| } | ||
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| List<INamedTypeSymbol> seen = new(); | ||
| foreach (var tds in receiver.Candidates) | ||
| { | ||
| var cSym = compilation.GetSemanticModel(tds.SyntaxTree).GetDeclaredSymbol(tds)!; | ||
| if (seen.Contains(cSym)) continue; // dedup partial classes | ||
| seen.Add(cSym); | ||
| var typeKeywords = tds.GetTypeKeywords(cSym); | ||
| if (typeKeywords.Contains("enum") || typeKeywords.Contains("interface") || typeKeywords.Contains("static")) continue; | ||
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| var nSpace = cSym.ContainingNamespace.ToDisplayString(); | ||
| var nSpaceDot = $"{nSpace}."; | ||
| List<string> innerText = new(); | ||
| var intfsToImplement = cSym.BaseType is not null | ||
| ? cSym.AllInterfaces.Except(cSym.BaseType.AllInterfaces) // superclass (or its superclass, etc.) already has the delegated base implementations of these interfaces' virtual methods | ||
| : cSym.AllInterfaces; | ||
| //TODO let an interface override a superinterface's virtual method -- may need to order intfsToImplement somehow | ||
| foreach (var methodParts in intfsToImplement.SelectMany(intfSym => Lookup(intfSym).Values)) | ||
| { | ||
| var methodSym = methodParts[0].MethodSym; | ||
| if (cSym.FindImplementationForInterfaceMember(methodSym) is not null) continue; // overridden | ||
| var memberImplText = $"{methodParts[0].ReturnType} {methodParts[0].MemberFullNameArgs.RemovePrefix(nSpaceDot)}"; | ||
| if (methodSym.MethodKind is MethodKind.Ordinary) | ||
| { | ||
| memberImplText += $"\n\t\t\t=> {methodParts[0].BaseImplNamePrefix.RemovePrefix(nSpaceDot)}{methodParts[0].InvokeCall};"; | ||
| } | ||
| else | ||
| { | ||
| if (methodParts[0].IsSetOrRemove) methodParts.Reverse(); | ||
| memberImplText += $"\n\t\t{{{string.Concat(methodParts.Select(methodNotes => $"\n\t\t\t{methodNotes.AccessorKeyword} => {methodNotes.BaseImplNamePrefix.RemovePrefix(nSpaceDot)}{methodNotes.InvokeCall};"))}\n\t\t}}"; | ||
| } | ||
| innerText.Add(memberImplText); | ||
| } | ||
| if (innerText.Count is not 0) context.AddSource( | ||
| source: $@"#nullable enable | ||
| namespace {nSpace} | ||
| {{ | ||
| public {string.Join(" ", typeKeywords)} {cSym.Name} | ||
| {{ | ||
| {string.Join("\n\n\t\t", innerText)} | ||
| }} | ||
| }} | ||
| ", | ||
| hintName: $"{cSym.Name}.VIMDelegation.cs"); | ||
| } | ||
| } | ||
| } |
26 changes: 26 additions & 0 deletions
26
ExternalProjects/BizHawk.SrcGen.VIM/VirtualMethodAttribute.cs
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| Original file line number | Diff line number | Diff line change |
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| @@ -0,0 +1,26 @@ | ||
| #nullable enable // for when this file is embedded | ||
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| using System; | ||
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| namespace BizHawk.Common | ||
| { | ||
| /// <summary> | ||
| /// Allows <see langword="abstract"/> methods in interfaces to be treated like <see langword="virtual"/> methods, similar to how they behave in classes. | ||
| /// And the same for <see langword="abstract"/> property accessors and <see langword="abstract"/> events (accessors in interface events are an error without DIM, apply to event). | ||
| /// </summary> | ||
| /// <remarks> | ||
| /// The base implementation can't be written into the interface, so it needs to be in a separate (usually inner) static class. A Source Generator will then add the necessary delegating method implementations at compile-time.<br/> | ||
| /// These faux-<see langword="virtual"/> methods support the same <see langword="override"/>/<see langword="sealed"/> mechanisms that you'd expect of classes: just apply the keyword as usual. | ||
| /// </remarks> | ||
| /// <seealso cref="BaseImplMethodName"/> | ||
| /// <seealso cref="ImplsClassFullName"/> | ||
| [AttributeUsage(AttributeTargets.Event | AttributeTargets.Property | AttributeTargets.Method, Inherited = false)] | ||
| public sealed class VirtualMethodAttribute : Attribute | ||
| { | ||
| /// <remarks>if unset, uses annotated method's name (with <c>_get</c>/<c>_set</c>/<c>_add</c>/<c>_remove</c> suffix for props/events)</remarks> | ||
| public string? BaseImplMethodName { get; set; } = null; | ||
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| /// <remarks>if unset, uses <c>$"{interfaceFullName}.MethodDefaultImpls"</c></remarks> | ||
| public string? ImplsClassFullName { get; set; } = null; | ||
| } | ||
| } |
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| Original file line number | Diff line number | Diff line change |
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| @@ -0,0 +1 @@ | ||
| ../.build_debug.sh |
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1 @@ | ||
| ../.build_release.sh |
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